Also in [1]} the singularities of the 6-point ziggurat were determined and found to comprise precisely those encoded in the “hexagon symbol alphabet” which is expected to suffice for expressing all 6-point amplitudes in SYM theory. Consequently, no massless planar 6-point Feynman integral, in any field theory, can have (first-type) Landau singularities anywhere other than on the vanishing locus of the hexagon symbol alphabet. In this paper we initiate a study of the singularities of the 7-point ziggurat and its connection to the “heptagon symbol alphabet” that, according to all evidence available to date [2]}, [3]}, [4]}, seems to suffice for expressing all 7-point amplitudes in SYM theory. However we emphasize that just like [1]}, our present analysis is completely general and is in no way tied to SYM theory.
